On Sun, 8 Oct 2000, Mitchell Blank Jr wrote:
> Dan Aloni wrote:
> >
> > I've been touring around the kernel sources when I stumbled
> > across the uid_hash_find() function (kernel/user.c):
> >
> > static inline struct user_struct *uid_hash_find(unsigned short uid, unsigned int
>hashent)
>
> Is it just me, or should that be "uid_t" not "unsigned short"? Now THAT
> looks like a bug.
>
You are right, that was the original function. The bug will typically show
in a system with more than a few tens of thousands of users.
So here's the complete patch for test9's kernel/user.c, including the
removal of the unnecessery initialization:
--- linux-2.4.0-test9/kernel/user.c Mon Oct 9 01:37:35 2000
+++ linux.vanilla/kernel/user.c Sun Oct 8 22:33:55 2000
@@ -51,22 +51,18 @@
*up->pprev = up->next;
}
-static inline struct user_struct *uid_hash_find(uid_t uid, unsigned int hashent)
+static inline struct user_struct *uid_hash_find(unsigned short uid, unsigned int
+hashent)
{
- struct user_struct *up, *next;
+ struct user_struct *up;
- next = uidhash[hashent];
- for (;;) {
- up = next;
- if (next) {
- next = up->next;
- if (up->uid != uid)
- continue;
- atomic_inc(&up->__count);
+ for (up = uidhash[hashent]; up ; up = up->next)
+ if (up->uid == uid)
+ {
+ atomic_inc(&up->__count)
+ return up;
}
- break;
- }
- return up;
+
+ return NULL;
}
/*
@@ -136,16 +132,11 @@
static int __init uid_cache_init(void)
{
- int i;
-
uid_cachep = kmem_cache_create("uid_cache", sizeof(struct user_struct),
0,
SLAB_HWCACHE_ALIGN, NULL, NULL);
if(!uid_cachep)
panic("Cannot create uid taskcount SLAB cache\n");
-
- for(i = 0; i < UIDHASH_SZ; i++)
- uidhash[i] = 0;
/* Insert the root user immediately - init already runs with this */
uid_hash_insert(&root_user, uidhashfn(0));
--
Dan Aloni
[EMAIL PROTECTED]
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